Urinary calculi affect roughly 1-5% of the population in the United States. Choletithiasis is found in 4-8% of people aged 40 and above. There are many devices available to entrap calculi and remove them from body cavities. Similarly there are many lithotripsy devices manufactured to fragment or fracture stones. Generally the former devices are composed of a basket or entrapment device that has three or more wires that are used to “trap” the stone. A working handle that remains extracorporeal is used to operate (mainly open and close) the wires. These devices are usually passed through an instrument, typically an endoscope, enabling the operator to directly visualize stone manipulation and/or entrapment.
It is generally recognized that urinary calculi less than or equal to 4 millimeters (mm) that make it into the ureter have an 85% chance of passing out of the urinary tract spontaneously without surgical intervention. The chance of spontaneous passage significantly diminishes as stone size increases. Stones greater than or equal to 8 mm rarely pass without interventional measures. Using only a basket or entrapment device is usually unsuccessful because the stone is too large to extract. As a result, some type of lithotripsy is typically employed.
Several prior art devices are known. For example, U.S. Pat. No. 5,064,428 to Cope et al. describes a device for retrieving calculi. The Cope et al. device includes a stone retrieval basket having three loops of nitinol wires that form a bulbous shape. The basket is connected to an inner tube having a hollow passageway. The basket and the inner tube may be inserted into a patient's body through an outer tube also having a hollow passageway. The basket may be enlarged within the body by pressing the basket against tissue. A physician then rotates and manipulates the basket to capture the calculi within the basket. Next, the inner tube is pulled outwards so that the basket collapses around the calculi and the calculi are drawn against an end of the outer tube. The physician can then insert a chemical or other well-known surgical means to dissolve, break up or crush the calculi. Fragments can be removed via the hollow passageway of the inner tube.
U.S. Pat. No. 5,403,324 to Ciervo et al. describes a device for retrieving calculi. The Ciervo et al. device includes a flexible catheter tube, and four wires pass through four hollow passageways within the catheter tube. On one end of the catheter tube, the wires exit to form a stone retrieval basket. On the other end of the catheter tube, the four wires are connected to a control mechanism that permits a physician to move the wires in and out of the catheter tube to enlarge and retract the basket. After the catheter tube is inserted in a patient's body, the physician manipulates the catheter to capture a calculus within the basket. Then, the basket is retracted to hold the calculus against the end of the catheter tube. Next, a laser or ultrasonic wire may be inserted through a fifth hollow passageway in the catheter tube to facilitate lithotripsy procedures.
U.S. Pat. No. 3,472,230 to Fogarty describes an umbrella catheter having a calculus retrieval basket comprising four spring wires that form an umbrella frame. The wires of the umbrella frame are normally bowed outwards to form a bulbous umbrella frame. The umbrella frame is partially covered on a distal end of the basket by a flexible material, such as a moldable elastomer. A control wire passes through a flexible catheter tube and is connected to a proximal end of the umbrella frame. When the control wire is pulled using a handle, the four spring wires are pulled into the catheter tube, and the umbrella is collapsed. When the control wire is pushed, the spring wires expand and the umbrella is opened. With the umbrella closed, a physician may position the umbrella beyond the location of stones or debris. Then, the physician may open the umbrella and withdraws the device a short distance to scoop up the debris. Next, the physician closes the umbrella and removes the device from the body with the stones within the umbrella.
U.S. Pat. No. 4,997,435 to Demeter describes a percutaneous catheter with an encapsulating receptacle. The Demeter device includes a first catheter with several struts connected to one end of the first catheter. The struts form a cup-shape with an opening distal from the end of the first catheter. A pocket shaped sheath is connected to the struts such that a receptacle is formed with an opening in the distal direction. A proximal portion of the sheath is connected to a second catheter passing within the first catheter. The second catheter is slidable and rotatable within the first catheter. With the struts and sheath in an untensioned condition, the opening of the receptacle is opened. But when the first catheter is rotated relative to the second catheter, the sheath twists relative to the struts causing the receptacle opening to close at the distal end. Thus, a physician can maneuver the device with the receptacle opened to capture a calculus within the receptacle. Then, the receptacle can be closed to encapsulate the calculus. The second catheter includes a lumen through which devices, such as grasping forceps, a scope, or a lithotripsy device can be inserted into the interior of the sheath.
U.S. Pat. No. 6,752,811 to Chu et al. describes several different laser-resistant medical retrieval devices. For instance, one device includes a bulbous-shaped basket formed by laser-resistant basket legs. The basket can be collapsed by retracting the basket legs within a catheter. Chu et al. explains that the basket legs can be made from or coated with laser resistant materials such as fluorocarbon plastics, ceramics, or plating of gold, silver or nickel. A laser lithotripter can be passed through the device into the basket. Chu et al. also describes a device in which the basket is partially covered on its distal end with a laser resistant fabric such as polytetrafluoroethylene (EPTFE), polytetrafluoroethylene (PTFE), tetrafluoroethylene (TFE), fluorinated ethylenepropylene (FEP), perfluoroalkoy (PFA), ethylene tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF).